黏土分层特性对吸力嵌入式板锚埋深损失的影响

Influence of Clay Layering Properties on the Embedment Loss of Suction Embedded Plate Anchors

海洋工程中,海床土体常伴有分层现象。将均质土、正常固结土在海床土体中的分布情况称之为土体分层特性。基于耦合的欧拉-拉格朗日(CEL)法,建立起用于分析不同土体分层特性的条件下,吸力嵌入式板锚(SEPLA)旋转调节过程的大变形有限元模型。通过与离心机实验及数值模拟结果对比,验证了模型的有效性。以双层黏土为例,研究了不同黏土分层特性下板锚的埋深损失。明确了衡量黏土分层特性的指标s_(u1,ave)/s_(u2,0),并考察了不同s_(u1,ave)/s_(u2,0)下,系缆点距土层分界线的距离d对板锚埋深损失的影响。研究结果表明:在s_(u1,ave)/s_(u2,0)>1的双层黏土中,随着d值的增大,板锚的埋深损失逐渐减小,当d≤-0.5B与d≥1B时,板锚的埋深损失分别仅受上层土体与下层土体强度影响;在s_(u1,ave)/s_(u2,0)<1的双层黏土中,随着d值的增大,板锚的埋深损失先增大后减小,当d=1B时,埋深损失存在一极大值ΔZ_(max),该极大值比板锚在单层土体中的埋深损失大32%~123%。同时,在s_(u1,ave)/s_(u2,0)<1的双层黏土中,板锚的埋深损失与上层土体的平均强度s_(u1,ave)和锚埋深处的土体强度sue有关;由于板锚埋深损失存在极大值ΔZ_(max),在工程中较为危险,因此,考察了强度比s_(u1,ave)/sue、埋深处土体强度sue、板锚初始埋深H对ΔZ_(max)的影响。

In marine engineering,seabed soils often exhibit layering phenomena.The distribution of homogeneous soil and normally consolidated soils in seabed soils is referred to as soil layering proper-ties.Based on the Coupled Eulerian-Lagrangian(CEL)method,a large deformation finite element model was established to analyze the rotational adjustment process of the suction embedded plate an-chors(SEPLA)under different soil layering properties.The validity of the model was verified through comparison with centrifuge tests and numerical simulations.The embedment loss of plate anchors un-der different clay layering properties was investigated by using double-layered clay as an example.The index s_(u1,ave)/s_(u2,0) was defined to measure the clay layering properties,and the influence of the distance d from the mooring point to the soil layer interface on embedment loss of plate anchors was examined un-der different s_(u1,ave)/s_(u2,0) values.The results showed that in double-layered clay with s_(u1,ave)/s_(u2,0)>1,as d increased,the embedment loss of the plate anchors gradually decreased.When d≤-0.5B and d≥1B,the embedment loss was only affected by the strength of the upper and lower soil layers,respec-tively.In double-layered clay with s_(u1,ave)/s_(u2,0)<1,as d increased,the embedment loss of the plate an-chors initially increased and then decreased,reaching a maximum valueΔZ_(max) at d=1B,which was 32%to 123%larger than the embedment loss in the single-layered soil.Additionally,in the double-layered clay with s_(u1,ave)/s_(u2,0)<1,the embedment loss of the plate anchors was related to the average strength of the upper soil s_(u1,ave) and the soil strength at the anchor embedment depth sue.Due to the exis-tence of a _(max)imum embedment loss valueΔZ_(max),which poses a significant risk in engineering,the ef-fects of the strength ratio s_(u1,ave)/sue,the soil strength at the anchor embedment depth sue,and the initial embedment depth H of plate anchors onΔZ_(max) were investigated.